中文摘要：

氮是湿地生态系统重要生源要素,基于高光谱（350～2500 nm）遥感数据对其进行估算以实现湿地土壤全氮（TN）含量无损、快速和准确定量化具有重要意义。选取闽江河口湿地为研究区,于2013年5月,沿潮滩（高潮滩到中潮滩）采集16个土壤剖面80个样本,室内测定其光谱反射率和TN含量,并基于原始反射率（R）和光谱指数（比值指数RI、归一化指数NDI和差值指数DI）建立土壤TN含量高光谱估算模型,并进一步分析反射光谱与铵态氮（NH_4^＋-N）、硝态氮（NO_3^--N）、有机质（SOM）和电导率（EC）之间的关系,以期揭示河口湿地土壤TN含量估算的机理。结果表明：土壤光谱反射率在350～600 nm,表现为高潮滩〈中潮滩,而在600^2500 nm,表现为高潮滩〉中潮滩;闽江河口湿地土壤TN含量与R在500 nm附近相关关系较好,并在490 nm有最大相关系数（-0.508）;RI、NDI和DI大大提高了反射光谱与土壤TN含量的相关关系,其相关系数较高区域集中在600～1000 nm的波段组合,以RI（590,640）、RI（610,940）、NDI（940,590）、NDI（940,610）、DI（640,920）和DI（640,940）相关关系表现较好,能较好地实现研究区湿地土壤TN含量反演,其估算与检验模型r^2均大于0.610,RMSE均小于0.208,其中以RI（610,940）估算精度最好,估算与检验模型r^2分别为0.832和0.631,RMSE分别为0.178和0.202;闽江口湿地土壤TN含量与SOM含量密切相关是土壤TN含量估算的重要机理,而NH_4^＋-N、NO_3^--N和盐分含量对其估算精度影响不大。

英文摘要：

Nitrogen（ N） is an essential biogenic element in wetland ecosystems. It is very important to estimate total N（ TN） concentration in wetland soil by the hyper-spectral remote sensing data with nondestructive,quick and accurate quantification. In this study,Minjiang River estuarine wetland was chosen as the study area,and 80 samples of 16 soil profiles were collected along a hydrological gradient（ from high tidal to middle tidal flat） in May,2013. Soil spectral reflectance and TN concentration were determined in the laboratory. Estimation and validation models were constructed by original spectral reflectance（ R） and spectrum parameters including ratio index（ RI）,normalized difference index（ NDI） and deference index（ DI）. Moreover,the correlations of spectral reflectance with NH_4^＋-N,NO_3^--N,SOM and EC were analyzed in order to reveal the mechanism of estimating soil TN concentration based on hyper-spectral remote sensing data. The results showed that the spectral reflectance of middle tidal soil was higher than that of high tidal soil at 350- 600 nm,while the spectral reflectance of high tidal soil was higher than that of middle tidal soil at 600- 2500 nm. Soil TN concentration showed a significant correlation with R at near 500 nm; the highest correlation coefficient value was- 0. 508,occurring at 490 nm. The spectrum parameters of RI,NDI and DI were calculated by bands at 600-1000 nm respectively,which greatly improved correlation coefficients with TN concentration,especially RI（ 590,640）,RI（ 610,940）,NDI（ 940,590）,NDI（ 940,610）,DI（ 640,920） and DI（ 640,940）. The models built could well realize the inversion of wetland soil TN concentration in the study area,in which the determination coefficients（ r^2） and the root means square errors（ RMSE） were all larger than 0.610 and less than 0.208,respectively. The best estimate parameter was RI（ 610,940）,and the r^2 values of its estimation and validation models were 0. 832 and0.631,while RMSE values we